Question: Solve for $x$ : $3x + 9 = 9x + 10$
Answer: Subtract $3x$ from both sides: $(3x + 9) - 3x = (9x + 10) - 3x$ $9 = 6x + 10$ Subtract $10$ from both sides: $9 - 10 = (6x + 10) - 10$ $-1 = 6x$ Divide both sides by $6$ $\dfrac{-1}{6} = \dfrac{6x}{6}$ Simplify. $-\dfrac{1}{6} = x$